Increased life expectancy implies fundamental changes in the composition of populations, with a significant rise in the number of elderly people. These changes are likely to have a massive influence on the life of individuals and on society in general. Abundant evidence has clearly established an inverse association between age and cognitive performance, but the age at which cognitive decline begins is much debated. Recent studies concluded that there was little evidence of cognitive decline before the age of 60.
However, clinical studies demonstrate a correlation between the presence of amyloid plaques in the brain and the severity of cognitive decline. It would seem that these amyloid plaques are found in the brains of young adults.
Few assessments of the effect of age on cognitive decline use data that spans over several years. This was the specific objective of the study led by researchers from Inserm and the University College London.
As part of the Whitehall II cohort study, medical data was extracted for 5,198 men and 2,192 women, aged between 45 and 70 at the beginning of the study, monitored over a 10-year period. The cognitive functions of the participants were evaluated three times over this time. Individual tests were used to assess memory, vocabulary, reasoning and verbal fluency.
The results show that cognitive performance (apart from the vocabulary tests) declines with age and more rapidly so as the individual's age increases. The decline is significant in each age group.
For example, during the period studied, reasoning scores decreased by 3.6 % for men aged between 45 and 49, and 9.6 % for those aged between 65 and 70. The corresponding figures for women stood at 3.6% and 7.4% respectively.
The authors underline that evidence pointing to cognitive decline before the age of 60 has significant consequences.
"Determining the age at which cognitive decline begins is important since behavioural or pharmacological interventions designed to change cognitive aging trajectories are likely to be more effective if they are applied from the onset of decline." underlines Archana Singh-Manoux.
"As life expectancy continues to increase, understanding the correlation between cognitive decline and age is one of the challenges of the 21st Century" she adds.
INSERM (Institut national de la sant� et de la recherche m�dicale): http://www.inserm.fr
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1. I'm 68 and have been thinking about these questions a lot as well as scanning my output a lot for signs of deterioration.
2. My cognitive functions (when thinking and/or writing about my main academic specializations) have changed over the past 10 y or so, assuming that I can evaluate the changes ~independently.
3. I don't think I've experienced noticeable memory, vocabulary, or reasoning changes.
4. Verbal fluency has changed not so much in the sense that the word(s) is not in my conscious&aware brain but in the sense that I think it takes longer for the word to be pulled out of its file and translated into speech. I think this must be a problem with some aspects of motor function since I don't use a keyboard efficiently any longer. Plaques could, of course, be the cause of the deteriorations I've described...unpleasant thought.
5. I guess #4 is directly related to deterioration in my ability to organize a project in my brain. It's not that I don't know what I want to say or, even, how I want to organize it all, but the process of getting there takes much longer and is not as automatic as it once was. Again, I'm pretty certain that the seriousness of this deficit depends on topic.
6. I realize that N= 1 + opinion is not reliable; however, this is a "hot" topic for me, and the thought of an inevitable (?) "tipping point" is not pleasant.
7. IMO Eliot Tucker-Drob UT Austin has some very neat data on related topics. The two graphs displayed on his lab page are, by way of thinking about it, compelling.